Communication System, Base Station, Host Node, and Communication Method

ABSTRACT

An object of the present invention is to provide a communication system, a base station, a host node, and a communication method in order to address one or more of the above-described problems. A communication system according to the present invention is a communication system including: a base station ( 10 ) and a host node ( 40 ) that communicates with the base station ( 10 ). The base station ( 10 ) included in the communication system transmits to the host node ( 40 ) setting information indicating whether or not a paging message transmitted from the host node ( 40 ) can be transmitted to other base stations, and the host node ( 40 ) receives the setting information from the base station ( 10 ).

TECHNICAL FIELD

The present invention relates to call processing (paging processing) fora host node to call a mobile terminal.

BACKGROUND ART

As shown in FIG. 28, in an architecture of LTE (Long Term Evolution),eNBs 601 to 604, which are RAN nodes, are connected to an MME (MobilityManagement Entity) 610 and an S-GW (Serving Gateway) 620, which arenodes belonging to a core network. When incoming data is transmitted toUE (User Equipment) in an idle state, for example, a sequence as shownin FIG. 29 is conducted. Specifically, when the MME 610 receives aDownlink Data Notification from the S-GW 620, it transmits a pagingmessage to the eNBs 601 to 604. At this time, the MME 610 transmitsPaging to the eNB located in an area where the UE has newly registeredits location.

Here, the area where the UE has registered its location is representedby a TA (Tracking Area). The TA is an identifier (ID) indicating alogical location, and an operator can freely decide a size of an areacovered by the TA according to a region and a traffic condition.Generally, if an area covered by one TA is large, the number of eNBsunder control of the TA also tends to increase. In addition, even thoughthe UE at idle time moves between the eNBs belonging to the same TA,location registration is unnecessary. That is, the number of signalsconcerning location registration generated in the UE moving between theeNBs can be suppressed by increasing the area covered by the TA.

To summarize, when an incoming call to the UE is generated, the MMEtransmits the paging message to an area covered by a newest TA where theUE is located.

Although FIG. 29 shows four eNBs as an example for simplicity ofexplanation, generally, for example, from hundreds of to one thousandeNBs may be present in the area covered by the TA. In such a case, theMME transmits the paging message to all the eNBs. Namely, the MME musttransmit the paging message to from hundreds of to one thousand eNBswithin an extremely short time. As a result, a load on processing of thepaging message of the MME rapidly increases.

Non Patent Literature 1 discloses a proposal on paging optimization inwhich when one or more certain appropriate eNBs receive a paging messagefrom an MME, and the eNBs that have received the paging message transmitthe paging message to neighbouring eNBs instead of the MME in order toreduce a processing load in the MME. The proposal according to NonPatent Literature 1 has been discussed in 3GPP (3rd GenerationPartnership Project). This example is shown in FIG. 30.

FIG. 30 shows that when the eNB 601 receives the paging message from theMME, it transmits the paging message to the neighbouring eNBs 602 to 604instead of the MME 610.

CITATION LIST Non Patent Literature

-   Non Patent Literature 1: 3GPP TSG RAN WG3 Meeting#51 R3-060151    “Transferring a paging request message” February 2006

SUMMARY OF INVENTION Technical Problem

However, specifications concerning paging optimization have not beenexamined in detail yet. The inventor of the present invention has foundthat at least the following problems occur in relation to theabove-described paging optimization.

First, a problem occurs when the MME transmits the paging message to allthe eNBs under the control of the TA as usual. In this case, apredetermined eNB transmits the paging message transmitted from the MMEto neighbouring eNBs instead of the MME. As a result, one eNB receives aplurality of the same paging messages (the paging message from the MMEand the paging message from the eNB), and the eNB transmits two pagingmessages to a radio line. As a result, a precious radio resource iswastefully used (refer to FIG. 31). That is, there is a problem thatefficiency of utilization of the radio resource decreases.

Furthermore, it is considered that a problem occurs also when the eNBdoes not send the paging message to the neighbouring eNBs instead of theMME. For example, the MME transmits the paging message only to thepredetermined eNB. Next, if the eNB does not transmit the paging messagefrom the MME to the neighbour eNBs, UE under control of the neighbouringeNBs cannot receive the paging message (refer to FIG. 32). That is,there are eNBs that fail to receive the paging message. As mentionedabove, a fundamental cause of these problems is that the MME cannot knowwhether or not the eNB can send the paging message to the neighbouringeNBs instead of the MME.

An object of the present invention is to provide a communication system,a base station, a host node, and a communication method in order toaddress one or more of the above-described problems.

Solution to Problem

A communication system according to a first exemplary aspect of thepresent invention is a communication system including: a base stationand a host node that communicates with the base station, wherein thebase station transmits to the host node setting information indicatingwhether or not a paging message transmitted from the host node can betransmitted to other base stations, and the host node receives thesetting information from the base station.

A base station according to a second exemplary aspect of the presentinvention is a base station that communicates with a host node,including: a communication unit that transmits to the host node settinginformation indicating whether or not a paging message transmitted fromthe host node can be transmitted to other base stations.

A host node according to a third exemplary aspect of the presentinvention is a host node that communicates with a base station,including: a communication unit that receives from the base stationsetting information indicating whether or not a paging messagetransmitted from the host node to the base station can be transmitted toother base stations.

A communication method according to a fourth exemplary aspect of thepresent invention is a communication method including: generatingsetting information indicating whether or not a paging messagetransmitted from a host node can be transmitted to other base stations,and transmitting to the host node the setting information.

Advantageous Effects of Invention

According to the present invention, a communication system, a basestation, a host node, and a communication method that do not decreaseefficiency of utilization of a radio resource are provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a configuration diagram of a communication system according toan embodiment 1.

FIG. 2 is a configuration diagram of a base station according to theembodiment 1.

FIG. 3 is a configuration diagram of a host node according to theembodiment 1.

FIG. 4 is a configuration diagram of a communication system according toan embodiment 2.

FIG. 5 is a configuration diagram of a host node according to theembodiment 2.

FIG. 6 is a configuration diagram of a base station according to theembodiment 2.

FIG. 7 is a configuration diagram of a mobile terminal according to theembodiment 2.

FIG. 8 is a configuration diagram of a communication system according toan embodiment 3.

FIG. 9 is a configuration diagram of an eNB and an MME according to theembodiment 3.

FIG. 10 is a chart showing a flow of transmission processing of settinginformation according to the embodiment 3.

FIG. 11 is a configuration diagram of an S1 Setup Request according tothe embodiment 3.

FIG. 12 is a configuration diagram of an ENB CONFIGURATION UPDATEaccording to the embodiment 3.

FIG. 13 is a configuration diagram of a communication system accordingto an embodiment 4.

FIG. 14 is a chart showing a transmission procedure of a paging messageaccording to the embodiment 4.

FIG. 15 is a configuration diagram of the paging message according tothe embodiment 4.

FIG. 16A is a chart showing a transmission procedure of an S1 SetupRequest according to an embodiment 5.

FIG. 16B is a chart showing a transmission procedure of a paging messageaccording to the embodiment 5.

FIG. 17 is a configuration diagram of the S1 Setup Request according tothe embodiment 5.

FIG. 18 is a configuration diagram of an ENB CONFIGURATION UPDATEaccording to the embodiment 5.

FIG. 19 is a chart showing a transmission procedure of a paging messageaccording to an embodiment 6.

FIG. 20 is a configuration diagram of the paging message according tothe embodiment 6.

FIG. 21 is a configuration diagram of a communication system accordingto an embodiment 7.

FIG. 22 is a chart showing a procedure for transmitting a paging messageaccording to the embodiment 7.

FIG. 23 is a configuration diagram of a communication system accordingto an embodiment 8.

FIG. 24 is a chart showing a procedure for transmitting a paging messageaccording to the embodiment 8.

FIG. 25 is a configuration diagram of a communication system accordingto an embodiment 9.

FIG. 26 is a configuration diagram of the communication system accordingto the embodiment 9.

FIG. 27 is a configuration diagram of a communication system accordingto an embodiment 10.

FIG. 28 is a configuration diagram of a general communication system inLTE.

FIG. 29 is a chart showing a general procedure for transmitting a pagingmessage.

FIG. 30 is a chart showing a general procedure for transmitting thepaging message.

FIG. 31 is a chart showing a general procedure for transmitting thepaging message.

FIG. 32 is a chart showing a general procedure for transmitting thepaging message.

DESCRIPTION OF EMBODIMENTS Embodiment 1

Hereinafter, embodiments of the present invention will be explained withreference to drawings. A configuration example of a communication systemaccording to an embodiment 1 of the present invention will be explainedusing FIG. 1. The communication system of FIG. 1 has a base station 10and a host node 20. The host node 20 communicates with the base station10. The host node 20 is, for example, an apparatus that aggregates aplurality of base stations, and may relay communications between thebase station and a device belonging to a core network.

When the host node 20 receives data addressed to a mobile stationpresent under control of the base station 10, the host node 20 transmitsa paging message to the mobile station through the base station 10 inorder to call the mobile station. Usually, the host node 20 transmitsthe paging message to a plurality of base stations present in apredetermined area (for example, a TA) in order to call a target mobilestation. As methods to transmit a paging message to a plurality of basestations, there are a method in which a host node transmits the pagingmessage to the plurality of base stations, and a method in which thebase station that has received the paging message from the host nodetransmits the paging message to other neighbour base stations.

The base station 10 transmits to the host node 20 setting informationindicating whether or not the paging message transmitted from the hostnode 20 can be transmitted to other base stations. Furthermore, the hostnode 20 receives the setting information transmitted from the basestation 10. Although the plurality of base stations are present in thecommunication system, not all the base stations can transmit the pagingmessage transmitted from the host node 20 to the other base stations.Therefore, the base station transmits the setting information to thehost node 20 as mentioned above, and the host node 20 determines basedon the setting information whether or not the base station, which is adestination of the paging message, can transmit the paging message tothe other base stations.

Subsequently, a configuration example of the base station 10 accordingto the embodiment 1 of the present invention will be explained usingFIG. 2. The base station 10 has a control unit 11 and a communicationunit 12. The control unit 11 outputs to the communication unit 12 aninstruction message that instructs the communication unit 12 to transmitsetting information to the host node 20. The setting information is theinformation indicating whether or not the paging message transmittedfrom the host node 20 can be transmitted to the other base stations.Alternatively, the control unit 11 may generate setting information andoutput the generated setting information to the communication unit 12.

When the communication unit 12 receives the instruction message from thecontrol unit 11, it transmits the setting information to the host node20. In this case, the setting information may be previously held in thecommunication unit 12, or may be output to the communication unit 12from a storage unit (not shown) etc. that stores the settinginformation. Alternatively, when the communication unit 12 receives thesetting information from the control unit 11, it may transmit thereceived setting information to the host node 20.

Next, a configuration example of the host node 20 according to theembodiment 1 of the present invention will be explained using FIG. 3.The host node 20 has a control unit 21 and a communication unit 22. Thecommunication unit 22 receives setting information transmitted from thebase station 10. The control unit 21 stores in a memory etc. the settinginformation of the base station 10, which is a transmission source ofthe setting information. When setting information is received from theplurality of base stations in the communication unit 22, the settinginformation of the plurality of base stations is stored in the memoryetc.

As explained above, the base station 10 according to the embodiment 1 ofthe present invention can notify the host node 20 of its own informationon the setting information indicating whether or not the paging messagetransmitted from the host node 20 can be transmitted to the other basestations. Furthermore, the host node 20 can know whether or not the basestation 10 can transmit the paging message to the other base stationsbased on the setting information transmitted from the base station 10.

Embodiment 2

Subsequently, a configuration example of a communication systemaccording to an embodiment 2 of the present invention will be explainedusing FIG. 4.

The communication system of FIG. 4 has the base station 10, a basestation 40, the host node 20, and a mobile terminal 50. In addition, thebase station 10 and the base station 40 are configured so as to be ableto communicate with each other. The mobile terminal 50 is located in acell area formed by the base station 10 or the base station 40.Furthermore, the host node 20 receives data addressed to the mobileterminal 50, and transmits a paging message to the base station 10together with a paging optimization instruction in order to call themobile terminal 50. The paging optimization instruction is theinstruction to transmit to other base stations the paging message thathas been transmitted from the host node 20 to the base station 10.

The host node 20 of FIG. 5 indicates transmitting of the pagingoptimization instruction to the base station 10. The control unit 21instructs the communication unit 22 to transmit the paging optimizationinstruction. The communication unit 22 transmits the paging optimizationinstruction to the base station 10 based on the instruction from thecontrol unit 21.

Subsequently, a configuration example of the base station 10 accordingto the embodiment 2 of the present invention will be explained usingFIG. 6. Since the base station 40 has a configuration similar to that ofthe base station 10, a detailed explanation thereof is omitted. The basestation 10 has the control unit 11, the communication unit 12, a hostnode interface 13, and a base station interface 14. Since the controlunit 11 and the communication unit 12 are similar to the control unit 11and the communication unit 12 that have been explained in regard to thebase station 10 of FIG. 2, symbols the same as those attached to thelatter are attached to the former.

The host node interface 13 is the interface used for communication withthe host node 20. The communication unit 12 receives the pagingoptimization instruction from the host node 20 through the host nodeinterface 13.

The control unit 11 instructs the communication unit 12 to transmit thepaging message transmitted from the host node 20 to another base stationbased on the paging optimization instruction that the communication unit12 has received from the host node 20. The other base station, which isa transmission destination of the paging message, is, for example, thebase station 40.

The base station interface 14 is the interface used for communicationwith the base station 40. The communication unit 12 transmits the pagingmessage transmitted from the host node 20 to the base station 40 throughthe base station interface 14. In addition, the base station interface14 may be used for communication with a plurality of base stations otherthan the base station 40. In this case, the communication unit 12 maytransmit the paging message transmitted from the host node 20 to theplurality of base stations through the base station interface 14.

The communication unit 12 transmits the paging message to a mobileterminal located in the cell area formed by the base station 10. Whenthe mobile terminal 50 is located in the cell area formed by the basestation 10, a radio line is set between the communication unit 12 andthe mobile terminal 50. Similarly, the paging message is transmitted toa mobile terminal located in the cell area formed by the base station 40also in the base station 40. Therefore, when the mobile terminal 50 islocated in the cell area formed by the base station 40, a radio line isset between a communication unit of the base station 40 and the mobileterminal 50.

Next, a configuration example of the mobile terminal 50 according to theembodiment 2 of the present invention will be explained using FIG. 7.The mobile terminal 50 has a control unit 51 and a communication unit52. The communication unit 52 has an antenna 53 in order to receive aradio signal transmitted from the base station 10 or the base station40. The communication unit 52 receives a paging message from the basestation 10 or the base station 40 through the antenna 53.

The control unit 51 determines whether or not the paging messagereceived by the communication unit 52 is the paging message addressed toits own mobile terminal 50. If the control unit 51 determines that thepaging message received by the communication unit 52 is the pagingmessage addressed to its own mobile terminal 50, the control unit 51instructs the communication unit 52 to transmit a response message tothe paging message to the base station 10 or the base station 40. Inaddition, if the control unit 51 determines that the paging messagereceived by the communication unit 52 is not the paging messageaddressed to its own mobile terminal 50, the control unit 51 does notinstruct the communication unit 52 to transmit a response message.

When the communication unit 52 is instructed to transmit a responsemessage to the paging message received from the control unit 51, thecommunication unit 52 transmits the response message to the base station10 or the base station 40 through the antenna 53.

As explained above, the host node 20 according to the embodiment 2 ofthe present invention can transmit to the base station 10 the pagingoptimization instruction instructing the base station 10 to transmit thepaging message to the other base stations. As a result, the host node 20can explicitly inform the base station 10 whether or not the basestation 10 should carry out paging optimization processing. In addition,the base station 10 can determine whether to transmit the paging messageto the other base stations according to whether the base station 10 hasreceived the paging optimization instruction from the host node 20.

The embodiment 2 of the present invention may be carried out incombination with the embodiment 1. That is, when the host node 20receives from the base station 10 setting information indicating thatthe base station 10 can transmit the paging message to the other basestation (for example, the base station 40), the host node 20 maytransmit the paging optimization instruction to the base station 10.Furthermore, when the host node 20 receives from the base station 10setting information indicating that the base station 10 cannot transmitthe paging message to the other base station, the host node 20 may avoidtransmitting the paging optimization instruction to the base station 10.In this case, since the base station 10 has not received the pagingoptimization instruction, it does not transmit the paging message to theother base station. Alternatively, when the host node 20 receives fromthe base station 10 the setting information indicating that the basestation 10 cannot transmit the paging message to the other base station,the host node 20 may transmit to the base station 10 a message toinstruct the base station 10 not to perform paging optimization.

The embodiments 1 and 2 are combined with each other to carry out thepresent invention as described above, and thereby the host node cantransmit the paging optimization instruction to the base station thatsupports paging optimization. Therefore, the base station that hasreceived the paging optimization instruction can be prevented from nottransmitting the paging message to the other base stations, and thus thepaging message reliably reaches all the base stations.

Embodiment 3

Next, a configuration example when the communication system according tothe embodiment 1 is applied to architecture of LTE (Long Term Evolution)will be explained using FIG. 8. The architecture in the LTE of FIG. 8has eNBs (evolved Node Bs) 110 to 140, an MME 150, an S-GW 160, a PDN-GW170, an IP Service 180, and UE 190. The MME 150, the S-GW 160, and thePDN-GW 170 configure an EPC (Evolved Packet Core), and the eNBs 110 to140 (an eNB group) configure an EUTRAN. The IP Service 180 is a serviceplatform that a communication common carrier (an operator) configures inorder to provide services.

In the LTE architecture, interfaces between the eNBs 110 to 140 and theMME 150 are specified as an S1 interface. Similarly, interfaces betweenthe eNBs 110 to 140 and the S-GW 160 are also specified as the S1interface. An interface between the S-GW 160 and the PDN-GW 170 isspecified as an S5 interface, and an interface between the MME 150 andthe S-GW 160 is specified as an S11 interface. Furthermore, an interfacebetween the eNBs is specified as an X2 interface. An interface betweenthe UE 190 and the eNBs is specified as a Uu interface.

Note that in the following explanation, a paging message that the eNBtransmits to a neighbouring eNB instead of the MME is referred to as anX2 paging message, and a paging message transmitted from the MME to theeNB is referred to as an S1 paging message. Here, the neighbouring eNBis the eNB connected through the X2 interface.

Next, configuration examples of the eNB 110 and the MME 150 according toan embodiment 3 of the present invention will be explained using FIG. 9.Note that since the eNBs 110 to 140 have similar configurations, onlythe configuration example of the eNB 110 is explained in FIG. 9, whileexplanations of the eNBs 120 to 140 are omitted.

The eNB 110 has an MME interface 111, a controller 112, and a memory113. The memory 113 stores setting information on capability indicatingwhether or not the eNB 110 carries out paging optimization in which theeNB 110 transmits the X2 paging message to the neighbouring eNBs insteadof to the MME 150.

The MME interface 111 is the interface used to perform communicationwith the MME 150 (S1 interface). The controller 112 transmits to the MME150 the setting information on the capability indicating whether or notthe eNB 110 carries out Paging Optimization through the MME interface111.

The MME 150 has an eNB interface 151, a controller 152, and a memory153. The eNB interface 151 and the MME interface 111 are connected toeach other through the S1 interface. The controller 152 receives settinginformation of the eNB 110 transmitted from the eNB 110 through the eNBinterface 151. Furthermore, the controller 152 stores the settinginformation received from the eNB 110 in the memory 153. The MME 150, inaddition to being connected to the eNB 110 through the S1 interface, isalso connected to the eNBs 120 to 140. Therefore, the memory 153 alsostores setting information of the eNBs 120 to 140.

Subsequently, a flow of processing that transmits the settinginformation from the eNBs 110 to 140 to the MME 150 will be explainedusing FIG. 10. When the eNBs 110 to 140 are started up (activated) (S1,S3, S5, S7), they each transmit an S1 Setup Request to the MME 150,respectively (S2, S4, S6, S8).

Configuration information (Configuration) of each eNB is included in theS1 Setup Request. For example, a TA (Tracking Area) to which each eNBbelongs, an eNB-ID to uniquely identify the eNB in the communicationsystem, etc. are included in the configuration information.

Furthermore, a Paging Optimization Support Indicator is included in theS1 Setup Request. The Paging Optimization Support Indicator indicatescapability of whether or not the eNB supports the Paging Optimization.For example, when the Paging Optimization Support Indicator is set to beTrue, it indicates that the eNB supports the Paging Optimization, andwhen the Paging Optimization Support Indicator is set to be False, itindicates that the eNB does not support the Paging Optimization. Trueand False may be replaced with Yes and No, etc.

FIG. 10 shows that the eNBs 110 to 140 notify the MME 150 aboutsupporting the Paging Optimization. Here, a name of the PagingOptimization Support Indicator is one example of what the eNBs 110-140notify the MME 150 about and, for example, it may be a name of an X2Paging Support Indicator or may be a name suitable for such name.

Subsequently, a configuration example of the S1 Setup Request includingthe Paging Optimization Support Indicator will be explained using FIG.11. When the eNB supports Paging Optimization, an information element ofthe Paging Optimization Support Indicator is set to the S1 SetupRequest. When the eNB does not support the Paging Optimization, theinformation element of the Paging Optimization Support Indicator is notset to the S1 Setup Request. Alternatively, when the eNB supports thePaging Optimization, ENUMERATED (true) may be set to an IE type andreference of the Paging Optimization Support Indicator, and when the eNBdoes not support the Paging Optimization, ENUMERATED (false) may be setto the IE type and reference of the Paging Optimization SupportIndicator.

Next, an example of notifying of the Paging Optimization SupportIndicator using a message different from the S1 Setup Request will beexplained using FIG. 12. Usually, a function etc. supported in the eNBmay be changed by updating of a software in the middle of the eNBstarting up and operating. For example, Paging Optimization may besupported in the eNB by performing a software update. In this case, theeNB may notify the MME 150 that the eNB will support the PagingOptimization using an ENB Configuration Update.

A configuration example of the ENB Configuration Update including thePaging Optimization Support Indicator is shown in FIG. 12. When the eNBsupports the Paging Optimization by the updating of the software, theinformation element of the Paging Optimization Support Indicator is setto the ENB Configuration Update. Alternatively, when the eNB supportsthe Paging Optimization by the updating of the software, ENUMERATED(true) may be set to the IE type and reference of the PagingOptimization Support Indicator.

In addition, when the information element of the Paging OptimizationSupport Indicator is not set, or when ENUMERATED (false) is set to theIE type and reference of the Paging Optimization Support Indicator, theeNB does not support the Paging Optimization. A case where settingindicating that the eNB does not support the Paging Optimization isperformed in the ENB Configuration Update is, for example, a case where,although the eNB supports the Paging Optimization in a state before theENB Configuration Update is performed, the eNB does not support thePaging Optimization after the ENB Configuration Update is performed.

As explained above, notification of the setting information held by theeNB can be sent to the MME also in the LTE architecture by using thecommunication system according to the embodiment 3 of the presentinvention. Consequently, the MME can determine whether or not the PagingOptimization is supported in the eNB. Therefore, since notification ofthe paging message can be reliably sent to an eNB where a mobileterminal serving as a paging target may be located using the S1 pagingmessage and the X2 paging message, failure to transmit the pagingmessage to the mobile terminal in the eNB can be prevented.

Embodiment 4

Subsequently, a configuration example when the communication systemaccording to the embodiment 2 is applied to the architecture of LTE(Long Term Evolution) will be explained using FIG. 13. The communicationsystem according to an embodiment 4 has the eNB 110, the eNB 120, andthe MME 150. Here, components similar to those of FIG. 9 are explainedwith the same symbols as those in FIG. 9 attached thereto.

The memory 153 stores information on a paging optimization instruction.The eNB interface 151 is the interface used for communication with theeNB connected through the S1 interface. The controller 152 transmits thepaging optimization instruction stored in the memory 153 to apredetermined eNB through the eNB interface 151. The predetermined eNBis assumed to be the eNB 110 in FIG. 13. Furthermore, the memory 153also transmits the S1 paging message to the eNB 110.

The eNB 110 has the MME interface 111, the controller 112, the memory113, a base station interface 114, and a communication unit 115. The MMEinterface 111 is the interface used for communication with the MME 150connected through the S1 interface. The communication unit 115 storesthe paging optimization instruction received through the MME interfacein the memory 113.

The base station interface 114 is the interface used for communicationwith the eNB 120. The communication unit 115 transmits the S1 pagingmessage transmitted from the MME 150 to the eNB 120 through the basestation interface 114. In addition, the base station interface 114 maybe used for communication with a plurality of eNBs other than the eNB120. In this case, the communication unit 115 may transmit the S1 pagingmessage transmitted from the MME 150 to the plurality of eNBs throughthe base station interface 114.

When the communication unit 115 receives the paging optimizationinstruction together with the S1 paging message, it transmits the X2paging message to the eNB 120. The communication unit 115 furthertransmits the paging message to a mobile terminal located in a cell areaformed by the eNB 110. When the UE 190 is located in the cell areaformed by the eNB 110, a radio line is set between the communicationunit 115 and a communication unit 192 of the UE 190. Similarly, acommunication unit 125 transmits the paging message to a mobile terminallocated in a cell area formed by the eNB 120 also in the eNB 120.Therefore, when the UE 190 is located in the cell area formed by the eNB120, a radio line is set between the communication unit 125 of the eNB120 and the UE 190.

An MME interface 121, a controller 122, a memory 123, a base stationinterface 124, and the communication unit 125 that configure the eNB 120have functions similar to those of the components of the eNB 110.Therefore, detailed explanations thereof are omitted.

Next, a flow of paging processing upon the arrival of an incoming callaccording to the embodiment 4 of the present invention will be explainedusing FIG. 14. First, when Downlink data addressed to the UE 190 isgenerated in an idle state of the UE 190, the PDN-GW 170 connected to anexternal network receives the Downlink data, and transfers the Downlinkdata to the S-GW 160 (S11).

Next, when the S-GW 160 receives the Downlink data, it transmits to theMME 150 a Downlink Data Notification indicating the arrival of incomingdata (S12). When the MME 150 receives the Downlink Data Notification, ittransmits a Downlink Data Notification Ack to the S-GW 160 as a responsesignal (S13).

Here, referring to an A portion surrounded by a dotted line of FIG. 14,a flow of processing when the MME 150 recognizes that the eNB supportsPaging Optimization in the S1 Setup Request received at the time ofactivation of the eNB 110 will be explained. The A portion surrounded bythe dotted line of FIG. 14 shows a flow of processing when a pagingoptimization instruction is transmitted. The MME 150 sets “yes” to aninformation element of the Paging Optimization Indicator of the S1paging message that is transmitted to the eNB 110 (S14). When the eNB110 receives the S1 paging message in which “yes” has been set to theinformation element of the Paging Optimization Indicator, the eNB 110transmits the X2 paging message to the neighbouring eNBs (for example,the eNBs 120 to 140) through the X2 interface in addition totransmitting the paging message to a mobile terminal located in its owncell area (S15).

Next, a flow of processing when the MME 150 recognizes that none of theeNBs 110 to 140 support Paging Optimization will be explained, referringto a B portion surrounded by a dotted line of FIG. 14. The B portionsurrounded by the dotted line of FIG. 14 shows a flow of processing whenthe paging optimization instruction is not performed. The MME 150 sets“No” to the information element of the Paging Optimization Indicator ofthe S1 paging message that is transmitted to the eNBs 110 to 140 (S16).Here, when the eNBs 110-140 receive the S1 paging message in which “No”has been set to the information element of the Paging OptimizationIndicator, the eNBs 110 to 140 transmit the paging message to mobileterminals located in their own cell areas. In addition, the eNBs 110 to140 do not transmit the X2 paging message to the neighbouring eNBs. Inaddition, the eNB that does not support the Paging Optimization may notrecognize the information element itself of the Paging OptimizationIndicator of the paging message. In this case, the eNB ignores theinformation element of the Paging Optimization Indicator, and transmitsthe paging message to the mobile terminal located in its own cell area.

Processing of the B portion of FIG. 14 is performed, for example, whensome eNBs of the eNBs 110 to 140 do not support the Paging Optimization.In this case, the MME 150 transmits the S1 paging message to all theeNBs as shown in the B portion of FIG. 14, and thereby no eNB fails toreceive the paging message. Processing of the A portion of FIG. 14 maybe performed when all the eNBs 110 to 140 support the PagingOptimization, or when the eNB that does not support the PagingOptimization can be identified.

Subsequently, referring to FIG. 15, configuration examples of the pagingmessages (the S1 paging message and the X2 paging message) when thePaging Optimization Indicator is added thereto according to theembodiment 4 of the present invention will be explained. In FIG. 15, anexample is shown where ENUMERATED (yes, no . . . ) is set to the IE typeand reference, which is the information element of the PagingOptimization Indicator. When ENUMERATED (yes) is set, the PagingOptimization Indicator indicates that the eNB supports the PagingOptimization, and when ENUMERATED (no) is set, the Paging OptimizationIndicator indicates that the eNB does not support the PagingOptimization. In addition, ENUMERATED (yes, no . . . ) may be set asENUMERATED (true, false . . . ).

In addition, when the Paging Optimization Indicator is not present inthe paging message, the eNB that has received the paging message doesnot transmit the paging message to the neighbouring eNBs through the X2interface.

As explained above, the MME can appropriately set the eNB to which theMME transmits the S1 paging message by transmitting the S1 pagingmessage together with the Paging Optimization Indicator. That is, theMME can transmit the S1 paging message only to the eNB that is made toperform Paging Optimization. Therefore, the eNB can be prevented fromdoubly receiving both the S1 paging message and the X2 paging message.Consequently, the eNB can be prevented from transmitting a paging signalto the mobile terminal in an overlapping manner based on the respectivepaging messages. Consequently, wasteful use of a radio resource can beprevented.

In addition, although the phrase Paging Optimization Indicator is usedin the above-mentioned explanation, for example, a phrase “X2 Paging isapproved or disapproved” may instead be used.

In addition, the embodiment 4 may be carried out in combination with theembodiment 3. This is similar to the case where the embodiments 1 and 2are combined with each other to be carried out. That is, in a case wherethe MME does not understand whether or not the respective eNBs can carryout Paging Optimization, even though the MME transmits to the eNB the S1paging message in which “yes” has been set to the information element ofthe Paging Optimization Indicator, the X2 paging message is nottransmitted to the neighbouring eNBs when the eNB does not support thePaging Optimization. Therefore, the MME transmits to the eNB the S1paging message in which “yes” has been set to the information element ofthe Paging Optimization Indicator after understanding that the eNB isthe one that supports the Paging Optimization, and thereby the MME canmake the paging message reach all the eNBs.

Embodiment 5

Next, a communication system that solves a problem described below willbe explained in an embodiment 5. When all the eNBs under control of theMME 150 support Paging Optimization, the MME 150 cannot appropriatelyselect the eNB that the MME 150 instructs to transmit the X2 pagingmessage to the neighbouring eNBs instead, unless the MME 150 recognizeswhich eNB is adjacent to which eNB.

<Solution 1>

In order to solve the above-mentioned problem, as shown in FIG. 16A, theeNB 110 notifies the MME 150 of a neighbouring eNB list of the eNB 110together with setting information using an S1 Setup Request (S21).Information elements of a Global eNB ID and a TAI that identifies a TAto which the eNB belongs are included in the neighbouring eNB list.

Next, the MME 150 stores information on the eNB and the neighbouring eNBlist transmitted from the eNB 110 (S22). Next, the MME 150 transmits anS1 Setup Response to the eNB 110 (S23). The MME 150 decides the eNB towhich the MME 150 transmits the S1 paging message when an incoming callto the UE is generated based on the information on the eNB that hastransmitted the stored neighbouring eNB list and the neighbouring eNBlist. The MME 150, for example, may transmit the S1 paging message tothe eNB having the largest number of neighbouring eNBs so that thepaging message spreads early. Alternatively, the MME 150 may transmitthe S1 paging message to the eNB where it is most probable that the UEwill be located.

The eNB 110 that has received the S1 paging message from the MME 150transmits the paging message to a mobile terminal of a cell area of theeNB 110, and also transmits the X2 paging message to the neighbouringeNBs.

Here, a configuration example of information elements of the S SetupRequest is shown in FIG. 17. Neighbouring Information, the Global eNBID, and Supported TAs are added to the S1 Setup Request of FIG. 17.

Although the example where the neighbouring eNB list is transmittedusing the S Setup Request has been explained in FIG. 16A, theneighbouring eNB list may instead be transmitted using an ENBCONFIGURATION UPDATE. A configuration example of information elements ofthe ENB CONFIGURATION UPDATE is shown in FIG. 18. Similar to FIG. 17,the Neighbour Information, the Global eNB ID, and the Supported TAs areadded to the ENB CONFIGURATION UPDATE of FIG. 18.

<Solution 2>

In order to solve the above-mentioned problem, a list of eNBs oftransmission destinations is added to the S1 paging message transmittedby the MME 150 as shown in FIG. 16B. Here, a flow of processingdescribed in FIG. 16B will be explained.

First, when Downlink data addressed to the UE 190 is generated in anidle state of the UE 190, the PDN-GW 170 connected to an externalnetwork receives the Downlink data, and transfers the Downlink data tothe S-GW 160 (S31).

Next, when the S-GW 160 receives the Downlink data, it transmits to theMME 150 a Downlink Data Notification indicating the arrival of incomingdata (S32). When the MME 150 receives the Downlink Data Notification, ittransmits a Downlink Data Notification Ack to the S-GW 160 as a responsesignal (S33). Next, the MME 150 transmits an S1 paging message to theeNB 110 (S34). Here, an eNB list of the eNBs to which the MME 150 hastransmitted the S1 paging message is included in the S1 paging message.The Global eNB ID and the TAI are included in the eNB list. In step S34of FIG. 16B, TAI#1, the eNB 110 as a transmission destination eNB, aneNB 200 (not shown), and an eNB 210 (not shown) are shown.

When the eNB 1110 receives the S1 paging message, it transmits an X2paging message to the neighbouring eNBs that belong to the TAI#1 shownin the S1 paging message but are not included in the transmissiondestination eNB list. If the eNBs 120 to 140 belong to the TAI#1, theeNB 110 transmits the X2 paging message to the eNBs 120 to 140. In themanner as described above, the eNB 110 can prevent transmitting of theX2 paging message to the eNBs that have already received the S1 pagingmessage by receiving the transmission destination eNB list.

<Solution 3>

In order to solve the above-mentioned problem, processing of acombination of the solutions 1 and 2 may be executed. For example, asexplained in FIG. 16A, the MME 150 decides the eNB to which the MME 150transmits the S1 paging message based on the neighbouring eNB list.Furthermore, the MME 150 transmits the S1 paging message including theeNB list of the eNBs to which the MME 150 has transmitted the S1 pagingmessage to the eNB 110 which it has been decided is the transmissiondestination of the S paging message.

As explained above, the eNB notifies the MME of the neighbouring eNBlist by executing the processing described in the solutions 1 to 3, andthereby the MME can decide the appropriate eNB to which the MMEtransmits the S1 paging message. For example, the MME can decide the eNBso that the paging message spreads early. Furthermore, the MME notifiesthe eNB of the eNBs to which the MME has transmitted the S1 pagingmessage, and thereby the eNB can prevent transmitting of the X2 pagingmessage to the eNBs that have already received the S1 paging message.Consequently, transmission of a useless signal in a communicationnetwork can be prevented.

Embodiment 6

Next, a paging message transmission procedure according to an embodiment6 of the present invention will be explained, referring to FIG. 19. Thepaging message transmission procedure according to the embodiment 6 aimsat preventing overlapping reception of the X2 paging message in theeNBs.

Since steps S41 to S43 are similar to steps S31 to S33 of FIG. 16B,explanations thereof are omitted. In step S44, the MME 150 transmits theS1 paging message to the eNB 110. At this time, the MME 150 transmitsthe S1 paging message only to one eNB of the eNBs having the TAI servingas a transmission object of the paging message. That is, the MME 150transmits the S1 paging message only to one eNB of the eNBs belonging tothe same TA. In an example of FIG. 19, when the eNBs 110 to 170 arepresent as the eNBs having the TAI#1, the MME 150 transmits the S1paging message only to the eNB 110. In addition, the eNB 110 that hasreceived the S1 paging message transmits the paging message to a mobileterminal located in a cell area formed by the eNB 110.

Next, the eNB 110 transmits the X2 paging message to the neighbouringeNBs 120 to 140 connected through the X2 interface among the eNBs 120 to170, which are the TAI#1 (S45). At this time, the eNB 110 transmitstransmission destination information of the X2 paging message, so as toinclude it in the X2 paging message. For example, in the example of FIG.19, the eNB 110 notifies each of the eNBs 120 to 140 of the eNBs 120 to140 as the transmission destination information of the X2 pagingmessage. The eNBs 120 to 140 that have received the X2 paging messagetransmit the paging message to mobile terminals located in cell areasformed by the respective eNBs.

Next, the eNB 120 that has received the X2 paging message furthertransmits the X2 paging message to the neighbouring eNBs 150 to 170connected through the X2 interface (S46). The eNBs 150 to 170 that havereceived the X2 paging message transmit the paging message to mobileterminals located in cell areas formed by the respective eNBs.Furthermore, similarly to step S45, the eNB 120 notifies each of theeNBs 150 to 170 of the eNBs 150 to 170 as the transmission destinationinformation of the X2 paging message.

Next, a configuration example of information elements of a pagingmessage (for example, an X2 paging message) is shown in FIG. 20. Aninformation element of List of eNBs is added to the paging message ofFIG. 20, and information on an eNB of a transmission destination is setto the List of eNBs.

As explained above, the eNB also notifies about the transmissiondestination information of the X2 paging message when it transmits theX2 paging message. Consequently, the eNB that has received the X2 pagingmessage can exclude the eNBs that have already received the X2 pagingmessage from transmission objects of the X2 paging message, when itfurther transmits the X2 paging message to the neighbouring eNBs.Consequently, the eNB can avoid receiving the X2 paging message in anoverlapping manner.

For example, a case will be explained where the eNB 120 is connected tothe eNB 110 and the eNBs 130 to 170 through the X2 interface in theexample of FIG. 19. In this case, when the eNB 120 is notified by theeNB 110 that the eNB 110 has transmitted the X2 paging message to theeNBs 120 to 140, the eNB 120 can exclude the eNBs 130 and 140 from thetransmission objects of the X2 paging message. Consequently, the eNBs130 and 140 can avoid receiving the X2 paging message in an overlappingmanner.

Embodiment 7

Next, a configuration example of a communication system according to anembodiment 7 of the present invention will be explained, referring toFIG. 21. In the communication system of FIG. 21, the eNBs 110 to 140 inthe communication system of FIG. 8 are replaced with HeNBs (Home eNodeBs) 201 to 208, further, an HeNB-GW (HeNB-Gateway) 210 is arranged inorder to aggregate the HeNBs 201 to 204, and an HeNB-GW 211 is arrangedin order to aggregate the HeNBs 205 to 208. The other configurations ofFIG. 21 are similar to those of FIG. 8. The HeNB is installed in a homeetc. in the LTE architecture, and is used as a base station that coversa narrow range.

Interfaces between the HeNB-GW 210 and the S-GW 160 and between theHeNB-GW 210 and the MME 150 are specified as the S1 interface.Interfaces between the HeNB-GW 211 and the S-GW 160 and between theHeNB-GW 211 and the MME 150 are also similarly specified as the S1interface. Furthermore, an interface between the HeNB-GW and the HeNB isalso specified as the S1 interface. Interfaces between the HeNB-GWs andbetween the HeNBs are specified as the X2 interface.

In addition, although in FIG. 21, the HeNB-GWs 210 and 211 are arrangedin order to aggregate the HeNBs 201 to 208, the HeNB-GWs 210 and 211 maynot be arranged. The communication system in that case is thecommunication system in which the eNBs 110 to 140 in the communicationsystem of FIG. 8 have been replaced with the HeNBs 201 to 208.

Next, FIG. 22 shows a flow of paging message transmission processing inthe communication system of FIG. 21. Since steps S51 to S53 are similarto steps S1 to S13 of FIG. 14, detailed explanations thereof areomitted. Furthermore, since steps S54 and S55 are similar to step S14 ofFIG. 14, and step S56 is similar to step S15 of FIG. 14, detailedexplanations thereof are omitted.

Here, when the HeNB-GW 210 receives the S1 paging message in step S54,it may transmit the X2 paging message to another HeNB-GW (for example,the HeNB-GW 211) instead of the MME 150.

As explained above. Paging Optimization can be made to operate also inthe communication system having the HeNBs.

Embodiment 8

Next, a configuration example of a communication system according to anembodiment 8 of the present invention will be explained using FIG. 23.The communication system of FIG. 23 has HNBs (Home Node Bs) 301 to 308,an HNB-GW (HNB-Gateway) 310, an HNB-GW 311, and a CN (Core Network) 320.The CN 320 includes network devices specified in 3GPP, such as an SGSN(Serving General packet radio service Support Node), a GGSN (GatewayGeneral packet radio service Support Node), and an MSC (Mobile SwitchingCenter). The HNB is installed in a home etc. and is used as a basestation that covers a narrow range in a network specified by 3GPP. TheHNB is, for example referred to as a femto base station.

An interface between the HNB-GW and the CN is specified as an Iuinterface. An interface between the HNB-GWs is specified as an Iurhinterface. An interface between the HNB and the HNB-GW is specified asan Iuh interface. An interface between the HNBs is specified as the Iurhinterface.

In the communication network of FIG. 23, unlike the communicationnetwork of FIG. 21, a message corresponding to the S1 Setup Request isnot present as the message transmitted from the HNB-GW 310 or the HNB-GW311 to the CN 320. Therefore, it is set to the CN 320 by an operatorwhether or not the HNBs 301 to 308 and the HNB-GWs 310 to 311 supportPaging Optimization.

Next, FIG. 24 shows a flow of paging message transmission processing inthe communication system of FIG. 23. Since step S61 corresponds to stepS51 of FIG. 22, and steps S62 to S64 correspond to steps S54 to S56 ofFIG. 22, detailed explanations thereof are omitted.

Here, in the communication system of FIG. 23, it is set to the CN 320 bymanual operation of the operator whether or not the HNB and the HNB-GWsupport the Paging Optimization. However, when the number of HNBsincreases, there is a case where it cannot be set to the CN 320 whetheror not all the HNBs support the Paging Optimization. In such a case, aPaging Optimization Indicator is not included in a paging message(hereinafter, an Iu paging message) transmitted from the CN 320 to theHNB-GWs 310 and 311.

Meanwhile, in registration processing from the HNB to the HNB-GWexecuted at the time of startup of the HNB, the HNB can register withthe HNB-GW using an HNB Registration message whether or not the HNBsupports the Paging Optimization. In such a case, even if the PagingOptimization Indicator is not set to the Iu paging message transmittedfrom the CN 320, the HNB-GW 310 or 311 can set the Paging OptimizationIndicator to transmit a paging message (hereinafter, the Iuh pagingmessage) to the HNB.

Embodiment 9

Next, a configuration example of a communication system according to anembodiment 9 of the present invention will be explained, referring toFIG. 25. The communication system of FIG. 25 has NBs (Node Bs) 401 to408, an RNC (Radio Network Controller) 410, an RNC 411, and a CN 420.The CN 420 includes network devices specified in 3GPP, such as an SGSN,a GGSN, and an MSC, similarly to the CN 320.

An interface between the RNC and the CN is specified as the Iuinterface. An interface between the RNCs is specified as an Iurinterface. An interface between the RNC and the NB is specified as anIub interface. Since paging message transmission processing in thecommunication system of FIG. 25 is similar to the paging messagetransmission processing in FIG. 24, a detailed explanation thereof isomitted. In addition, although the communication system in which theRNCs 410 and 411 are arranged between the NBs 401 to 408 and the CN 420has been explained in FIG. 25, the RNC may be omitted as shown in FIG.26. In this case, an interface between the NB and the CN is specified asthe Iu interface. Furthermore, an interface between the NBs is specifiedas the Iur interface. Also in such a case, the paging messagetransmission processing in FIG. 24 can be applied.

Embodiment 10

Next, a configuration example of a communication system according to anembodiment 10 of the present invention will be explained using FIG. 27.The communication system of FIG. 27 has a configuration in which theHeNBs 205 to 208 and the HeNB-GW 211 in the communication system of FIG.21 are replaced with RNs (Relay Nodes) 521 to 524 and a DeNB (Donor eNB)530. The RN is a device that is connected to an eNB using wirelesscommunication in order to expand a coverage of the eNB, and relayscommunication between UE and the eNB. The DeNB is the eNB to which theRN is connected. Although an interface between the RN and the DeNB isspecified as a Un interface, the RN supports the S1 interface and the X2interface like the eNB. However, the X2 interface is not supportedbetween the RNs. The X2 interface in the RN is used for communicationwith the DeNB.

Here, when the S1 paging message transmitted from the MME 150 istransferred to the RN 521, it is considered that the RN 521 transmitsthe X2 paging message to the DeNB 530 through the X2 interface, and thatthe DeNB 530 transmits the X2 paging message to the RNs 522 to 524.However, the RN transmitting the X2 paging message to the neighbour RNsvia the DeNB as described above only uses a radio resource between theDeNB 530 and the RN, resulting in no advantage.

Accordingly, when the DeNB 530 receives from the MME 150 an S1 pagingmessage in which “yes” or “true” has been set to an information elementof the Paging Optimization Indicator, the DeNB 530 sets “no” or “false”to the information element of the Paging Optimization Indicator, andtransmits the paging message to the RNs 521 to 524. Alternatively, theDeNB 530 transmits the paging message to the RNs 521 to 524 withoutsetting the information element of the Paging Optimization Indicator.

In the communication system having the RN, wasteful use of the radioresource between the DeNB 530 and the RN can be prevented by setting theinformation element of the Paging Optimization Indicator as mentionedabove.

OTHER EMBODIMENT

In the above-mentioned embodiments, the eNB, the HeNB, the HeNB-GW, andthe RN, which are RAN (Radio Access Network) nodes, transmit the PagingOptimization Indicator to the MME or the host node, and notify the MMEor the host node of whether or not they support the Paging Optimization.In contrast with this, in order to understand whether or not a deviceunder control of the MME or the host node supports the PagingOptimization in the MME or the host node, the MME or the host node mayunderstand a support situation of the Paging Optimization of the RANnode by an operator's setting, i.e., O&M (or OAM: Operation andMaintenance) setting.

Note that the present invention is not limited to the above-describedembodiments, and that they can be appropriately changed withoutdeparting from the spirit of the invention.

In the above-mentioned explanation of the present invention, the presentinvention is described in detail in relation to the system related to3GPP (Third Generation Partnership Project) in order that those skilledin the art can more readily understand the invention. However, aprinciple of the paging processing can be applied to other systems, suchas other CDMA, WIMAX, or a wireless system.

Note that the above-described embodiments are configured such that thebase station notifies the host node of its own capability information.However, it is also possible to achieve the present invention by othermethods. Specifically, the present invention may be configured such thata node having an O&M function that manages the base station collectscapability information from the base station, and informs the MME of thecapability information.

Furthermore, although the present invention has been explained as ahardware configuration in the above-mentioned embodiments, it is notlimited to this, and it is also possible to achieve processing in thebase station or the host node by making a CPU (Central Processing Unit)execute a computer program. In this case, the computer program is storedusing various types of non-transitory computer readable media, and canbe supplied to a computer. The non-transitory computer readable mediainclude various types of tangible storage media. Examples of thenon-transitory computer readable medium include: a magnetic recordingmedium (for example, a flexible disk, a magnetic tape, a hard diskdrive); a magnetic optical recording medium (for example, a magneticoptical disk); a CD-ROM (Read Only Memory); a CD-R; a CD-R/W; and asemiconductor memory (for example, a mask ROM, a PROM (ProgrammableROM), an EPROM (Erasable PROM), a flash ROM, an RAM (random accessmemory)). In addition, the program may be supplied to the computer byvarious types of transitory computer readable media. Examples of thetransitory computer readable medium include an electrical signal, anoptical signal, and an electromagnetic wave. The transitory computerreadable medium can supply the program to the computer through a wiredcommunication channel, such as an electric wire and an optical fiber, ora wireless communication channel.

Hereinbefore, although the invention in the present application has beenexplained with reference to the embodiments, the invention in thepresent application is not limited by the above. Various changes thatcan be understood by those skilled in the art within the scope of theinvention can be made to a configuration and a detail of the inventionin the present application.

This application claims priority based on Japanese Patent ApplicationNo. 2012-182235 filed on Aug. 21, 2012, and the entire disclosurethereof is incorporated herein.

REFERENCE SIGNS LIST

-   10 base station-   11 control unit-   12 communication unit-   13 host node interface-   14 base station interface-   20 host node-   21 control unit-   22 communication unit-   40 base station-   50 mobile terminal-   51 control unit-   52 communication unit-   53 antenna-   110 to 140 eNB-   111 MME interface-   112 controller-   113 memory-   114 base station interface-   115 communication unit-   121 MME interface-   122 controller-   123 memory-   124 base station interface-   125 communication unit-   150 MME-   151 eNB interface-   152 controller-   153 memory-   160 S-GW-   170 PDN-GW-   180 IP Service-   190 UE-   301 to 308 HNB-   310, 31 HNB-GW-   320 CN-   401 to 408 NB-   410, 41 RNC-   420 CN-   521 to 524 RN-   530 DeNB

1-30. (canceled)
 31. A host node in a communication system comprising: areceiver configured to receive a first message from a first basestation, the first message including first information and secondinformation, the first information indicating a list including at leastone neighbor base station and the second information indicating whethereach of the neighbor base station can send a paging message to otherbase station; and a transmitter configured to transmit a second messagefor paging to a second base station, the second message including thirdinformation indicating at least one base station to which the host nodehas transmitted a paging message.
 32. The host node according to claim31, further comprising: a processor configured to determine the secondbase station based on the first message.
 33. The host node according toclaim 31, wherein the list further includes ID information whichindicates ID of one of the neighbor base stations.
 34. The host nodeaccording to claim 31, wherein the list further includes informationrelated to Supported TAI.
 35. A base station in a communication systemcomprising: a transmitter configured to transmit a first message to ahost node, the first message including first information and secondinformation, the first information indicating a list including at leastone neighbor base station and the second information indicating whethereach of the neighbor base station can send a paging message to otherbase station; and a receiver configured to receive a second message forpaging from the host node, the second message including thirdinformation indicating at least one base station to which the host nodehas transmitted a first paging message.
 36. The base station accordingto claim 35, the transmitter further configured to transmit a secondpaging message to other base station, information of the other basestation is not included in the third information.
 37. The base stationaccording to claim 35, wherein the list further includes ID informationwhich indicates ID of one of the neighbor base stations.
 38. The basestation according to claim 35, wherein the list further includesinformation related to Supported TAI.
 39. A base station in acommunication system comprising: a receiver configured to receive afirst message for paging from a host node, the first message includingfirst information indicating at least one base station to which the hostnode has transmitted a first paging message; and a transmitterconfigured to transmit a second paging message to other base station,information of the other base station is not included in the firstinformation.